Process for disposal of volatile hazardous wastes

ABSTRACT

A method of disposing of hazardous volatile liquid organic waste materials that includes the steps of providing a dry free flowing solid material containing lime and preferably, an organic salt of calcium, magnesium or aluminum containing about 10 to 22 carbon atoms; stirring a volatile organic liquid waste material to be disposed of therein to form a non-aqueous paste; allowing the paste to harden into a solid form that does not release the waste liquids when 100 grams thereof are placed in a 400 micron conical paint filter for five minutes: and, burning the resultant solid whereby the volatile material is burned and any hazardous metallic impurities remain in the resultant lime-based ash. The preferred organic salt component is calcium stearate.

FIELD OF THE INVENTION

This invention relates to the disposal of volatile liquid organic wastematerials. More specifically, the invention relates to a method ofconverting such hazardous liquid materials which may contain hazardousmetallic salts into a solid form that can be burned without release ofthe hazardous metallic compounds into the atmosphere.

BACKGROUND OF THE INVENTION

Many commercial operations, particularly those involving painting resultin hazardous volatile organic waste by-products. Such wastes includesolvents that contain hazardous metallic compounds such as silvernitrate, chromium compounds and the like. The presence of the metalliccompounds has resulted in the prohibition of burning of said materialsexcept under very carefully controlled conditions due to the fact thatthe metallic compounds can be released into the atmosphere duringcombustion thereby creating health-threatening environmental pollution.

Heretofore it has been necessary to transport the materials, usually forseveral hundred miles at great cost for purposes of disposal. Variousproposals have heretofore been made to mix hazardous materials into anaqueous slurry than is hardened into a cementitious form suitable forlandfill disposal. These methods suffer, however, from the possibilitythat both the volatile organic liquids such as paint thinners and thesuspended solid metallic waste materials can eventually be leached intothe soil and thus may contaminate the ground water Disposal of the wastematerials has therefore continued to be a costly proposition.

SUMMARY OF THE INVENTION

It is a principal object of the present invention to convert hazardousvolatile organic waste materials into a non-hazardous solid state inwhich they can be used as fuel pellets A related aspect of the inventionis to provide such fuel pellets which during combustion retains solidhazardous metallic salts within the non-combustible solid component orash remaining after combustion of a pellet. A further related aspect ofthe invention is to provide a process for disposing safely of a widevariety of hazardous organic waste materials such as paint thinners,solvents, paints, reducers, glues, adhesives, wood preservatives,varnishes, stains, wastes such as liquid components urethanes, epoxies,epoxy primers, acrylic enamels, acrylic lacquers, alkyd enamels, acrylicurethanes, and the like in a safe manner. A further aspect of theinvention relates to the conversion of such materials into a pellet formwhich can be burned to regain the heating value of the waste materialwhile inhibiting the release into the atmosphere of any suspendedhazardous solid metallic materials.

A further related aspect of the invention is to provide a process fordisposing of the hazardous wastes classified by the EPA as D001, F003,F002, D011, D006, D007, D008, or F032. A further related aspect of theinvention relates to conversion of all of these hazardous liquidmaterials into a solid form from which the organic material does notleach but yet which can be disposed of safely by combustion. A stillfurther related aspect involves the conversion of the hazardous wastematerials into solidified pellet form in which there is no free standingliquid and from which the organic liquids do not leach.

A yet further aspect of the invention involves forming of the materialsinto a combustible pellet form that repels water. Yet another relatedaspect of the invention relates to disposing of volatile liquidmaterials that contain hazardous solid organic salts such as silver,cadmium, chromium, lead or arsenic salts.

Briefly summarized, the invention relates to a method of disposing ofhazardous volatile liquid organic waste materials that includes thesteps of providing a dry free flowing solid material containing lime andpreferably, an organic salt of calcium, magnesium or aluminum containingabout 10 to 22 carbon atoms; stirring a volatile organic liquid wastematerial to be disposed of therein to form a non-aqueous paste; allowingthe paste to harden into a solid form that does not release the wasteliquids when 100 grams thereof are placed in a 400 micron conical paintfilter for five minutes: and, burning the resultant solid whereby thevolatile material is burned and any hazardous metallic impurities remainin the resultant lime-based ash. The preferred organic salt component iscalcium stearate.

DETAILED DESCRIPTION

The volatile organic industrial wastes dealt with in accordance with thepresent ion include those resulting from painting operations such asthose used by the furniture or window manufacturing industries or any ofa myriad of metallic articles that are painted during the course ofmanufacturing operations. The solvents used commonly includemethylisobutylketone (MIBK), petroleum distillates, mineral spirits andxylene. Other examples include ethylbutylacetate, n-butylacetate,neosol, kerosene, vinyl sprays, two component paint top coats containingcatalysts, polyurethane acrylic epoxy or alkyd components or finishes,other wastes include volatile organic materials that remain asbyproducts from various chemical processing operations. The volatilewastes can contain various metallic compounds such as silver, chromium,mercury, lead, arsenic, antimony, cadmium, molybdenum, cobalt, manganeseor various heavy metals, any or all of which are hazardous if dischargedinto the atmosphere, for example, by conventional combustion operations.Due to these problems, disposal of the materials has been a costlyproposition.

In accordance with the present invention, the volatile, metal compoundcontaining organic materials are bound in a matrix material, the majorcomponent of which a weight basis is lime. Ordinary barn lime whichconsists of approximately 97-98% by weight of calcium carbonate or quicklime is satisfactory for this purpose. A dry non-leaching solid can beformed using lime alone in the case of some organic waste liquids.However, in accordance with the preferred embodiment of the invention,it has been found that a solid water repellant form of pellet can beformed by using a mixture of lime and an organic salt of magnesium,calcium or aluminum in which the organic component of the salt hasbetween 10 and 22 carbon atoms. The preferred such salt material iscalcium stearate. Other calcium salts having between about 10 and 22carbon atoms can be substituted, however. The most notable of these arecalcium palmitate and calcium oleate. Magnesium or aluminum stearate,palmitate or oleate can also be substituted. The other salts havingbetween 10 and 22 carbon atoms can also be substituted.

While the exact mechanism of the present invention is not fullyunderstood, it appears that the volatile organic materials when mixedwith lime and the metallic organic salts referred to in a non-aqueousmixture appear to have some affinity for the matrix materials whichappear to have a degree of water repellency.

In accordance with the invention the matrix material containing lime andthe metallic organic salts such as calcium stearate are mixed togetherin a dry particulate form. After mixing, the materials revert to a solidstate from which no free liquid is leached, as determined by the paintfilter test protocol wherein a 100 ml sample of a composition containingthe volatile waste material is placed in a 400 micron conical paintfilter for five minutes. Compositions of this invention are non-aqueousand thus no water passes through the filter. Surprisingly, however, novolatile organic material passes through the filter. This is true evenwhen the test is conducted for a period of several hours rather thanonly five minutes.

The solid pellets obtained by the process of this invention can besafely disposed of by combustion on many industrial premises. Theinvention further provides pellets which when combusted provide a meansfor recovery of fuel values from the waste organic materials. It is alsobelieved that the organic salt constituent of the matrix material isalso combusted to form carbon dioxide and water. Any suspended hazardousmetal salt materials remain trapped in the ash component which ash isprimarily composed of lime and which depending on the type of metalorganic salt used can also contain magnesium oxide or aluminum oxide.The preferred compositions of the present invention include a matrix orbinder material that contains one part of calcium stearate by volume toone to four parts of lime. Since the lime is more dense, the lime willconstitute an even larger percentage of the material on a weight basis.It is preferred that one part of volatile waste material mixed withthree to four parts by volume of the binder material.

The binder material is in the form of a free flowing solid which may bedescribed as granular or powdery in form. While particle size is notcritical, it is preferred that the materials be relatively finelydivided granules or powder to facilitate mixing of the ingredients.

Any method of mixing the materials can be employed on a commercialbasis. Grinding as in a hammer mill or by use of a shredder are examplesof suitable mixing procedures. For easy combustion, it is preferred thatthe material be formed into pellets or briquettes similar in size tothose used for other fuels such as coal, charcoal or the like.

Specific examples illustrating the practice of the invention are setforth in the following examples.

EXAMPLE 1

A hazardous waste material recovered from a commercial paintingoperation and containing volatile methylisobutylketone (MIBK) withsuspended silver nitrate and other suspended solids was mixed in theratio of one part of the volatile waste material to three and one-halfparts by volume of a mixture containing 50% by volume of HurlbutNon-Slip Barn Lime produced by Great Lakes Calcium Corporation of GreenBay, Wisc. which according to the manufacturer consisted ofapproximately 98% by weight calcium carbonate and an equal amount byvolume of calcium stearate 15F sold under the trade name SYNPRO® bySynthetic Products Company of 1000 Wayside Road, Cleveland, Ohio. Thelime and the calcium stearate were completely mixed by tumbling. Themixture was added as a powdery material free of water to the volatileorganic material and stirred to form a paste. The paste hardened at roomtemperature within approximately five minutes. One hundred millilitersof the resultant solid material was placed in a 400 micron conical paintfilter for a period of four hours without leaching of any of the liquidmaterial. No free standing liquids were visible. The pellets could beburned at an elevated temperature. Once combustion was initiated thepellets supported a flame. After combustion the silver nitrate and othersolid metallic waste materials were found to be contained within thecalcium containing ash but remained after combustion.

EXAMPLE 2

The same waste material was mixed with the following calcium containingmaterials: (a) 1.5 parts by volume of Hurlbut Non-Slip Barn Lime to 1part of calcium stearate 15F; (b) 2 parts of Hurlbut Non-Slip Barn Limeto 1 part of calcium stearate 15F; (c) 2.5 parts of Hurlbut Non-SlipBarn Lime to 1 part of calcium stearate 15F; and (d) 3 parts of HurlbutNon-Slip Barn Lime to 1 part of calcium stearate 15F. Each of theresultant mixtures hardened into a pellet on which no free liquid wasobserved and from which no liquid leached when tested in a conicalfilter as described in Example 1.

Best results were obtained by adding 3.5 parts by volume of the calciumbinder material to 1 part by volume of the volatile hazardous wastematerial.

What is claimed is:
 1. A method of disposing of hazardous metal compoundcontaining volatile liquid organic waste materials consistingessentially of:providing a dry, free flowing solid material consistingessentially of a mixture of lime or calcium carbonate and an organicsalt of calcium, magnesium or aluminum having between 10 and 22 carbonatoms, stirring a volatile organic liquid waste material therein to forma non-aqueous paste, allowing said paste to harden into a solid formthat does not release said volatile liquid organic waster material when100 grams thereof are placed in a 400 micron conical paint filter forfive minutes, and burning said resultant solid whereby said volatileliquid organic waste material is burned and the residue of said solidmaterial remains as an ash.
 2. A method according to claim 1 wherein thefree flowing solid material comprises a mixture of barn lime and saidcalcium, magnesium or aluminum salt.
 3. A method according to claim 2wherein said calcium salt comprises calcium stearate.
 4. A methodaccording to claim 3 where said calcium carbonate or lime and calciumstearate are present in said material in approximately equal amounts byvolume.